I'm trying to stream FILESTREAM data from an unsafe SQL CLR assembly. The connection string is Data Source=LAPTOP2\SQLEXPRESS;Initial Catalog=test;Integrated Security=True;Enlist=False When creating a new SqlFileStream (inside a SqlTransaction, of course), I'm getting: The request is not supported at OpenSqlFilestream. So I decided to try native OpenSqlFilestream, but then I'm getting an invalid handle (-1) while GetLastWin32Error returns that same: The request is not supported (ERROR_NOT_SUPPORTED). I have also tried SqlContext.WindowsIdentity.Impersonate() with no apparent effect. I couldn't find any documentation referencing this restriction. Is it really unsupported? If it is unsupported, is there a good reason? Does anyone know of a workaround?